What is hallux valgus and how is it evaluated for surgery?
Hallux valgus is the most common affliction of the normal adult foot. It is a condition where the large toe is deviated laterally with the first metatarsal head deviated medially causing bunion deformity. The hallux valgus angle is measured by a line drawn through the proximal phalanx of the large toe and through the first metatarsal. A normal angle is 0 to 15 degrees with moderate (>25 degrees) and severe (>35 degrees) deformities commonly occurring.
The cause of hallux valgus can be attributable to heredity, especially in combination with a short big toe relative to the second toe (Greek foot). Other congenital causes include pes planovalgus (flat feet) and metatarsus primus varus. The intermetatarsal angle between the first and second metatarsals is measured by a line drawn through the first and second metatarsals. The intermetatarsal angle is normally 0 to 10 degrees, whereas angles >16 degrees are moderate and >21 degrees are severely deformed. The need for surgical correction is considered if the painful deformity interferes with a patient’s lifestyle or ability to wear shoes and there is a failure of conservative management (wider toe box shoes). There are over 100 different operations for correction of hallux valgus. The choice depends on the surgeon’s skill and how the deformity needs correction (i.e., proximal metatarsal wedge osteotomy if intermetatarsal angle too great, etc.). Implant arthroplasty does not provide reliable long-term results compared with arthrodesis (15 degrees valgus, 25 degrees dorsiflexion).